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UCC28711: Transformer Design for UCC28711.

Mabonga Paul
Intellectual 300 points
Part Number: UCC28711
Other Parts Discussed in Thread: TIDA-00173, UCC28700,

I am designing a power supply system, 40W, 20V output with Vin of 400V - 700V using the UCC28711 as is demonstrated in TIDA-00173. I however have face a problem of failing to find a custom designed transformer for example, no distributor of wurth electronics stocks the 750342585 transformer that's used in TIDA-00173 reference design. 

I was thinking about designing a power supply using the UCC28711 around a given transformer spec. In effect, I find a transformer that's being supplied by a distributor then use the equations in TIDA-00173 and the datasheet of UCC28711 to come up with values of other components such as resistors instead of using the design equations to come up with a transformer spec. Am doing this so as to prevent a situation where I have to make my own transformer as it may have high parasitic capacitances and leakage inductance. 

Please advice o whether the method I have stated above is valid. 

  • 0
    TI__Guru 65765 points

    Hello,

    There was an application note written on how to design with the UCC28700 PSR controller and goes through an off line design 85 to 265V RMS down to 5V 5W regulated output.  Including transformer turns ratio, RMS current and primary magnetizing inductance selection.  It can be found at the following link.  The UCC28711 just has a different maximum switching frequency.

    The UCC2871x family of devices also has an excel design tool that can be used at the following link that can help with the design.  I know it is ac to dc.  If you are doing a DC to DC you can use the tool by dividing your peak input voltages by (2)^0.5 and you should be able to use the tool. www.ti.com/.../sluc675

    I am sorry that you are having issues matching the tida design transformer calculations.  However, the excel tool for the UCC2871x devices was used to design the UCC28711 EVM. UCC28711EVM-160 can be found at the following link. The http://www.ti.com/lit/ug/sluua12/sluua12.pdf.  You can use this as a reference to double check your calculations.

    Regards,